The Moon will pass close to the Sun and become lost in the Sun's glare for a few days.
The Moon's orbital motion carries it around the Earth once every four weeks, and as a result its phases cycle from new moon, through first quarter, full moon and last quarter, back to new moon once every 29.5 days.
This motion also means that the Moon travels more than 12° across the sky from one night to the next, causing it to rise and set nearly an hour later each day. Click here for more information about the Moon's phases.
At new moon, the Earth, Moon and Sun all lie in a roughly straight line, with the Moon in the middle, appearing in front of the Sun's glare. In this configuration, we see almost exactly the opposite half of the Moon to that which is illuminated by the Sun, making it doubly unobservable because the side we see is unilluminated.
Over coming days, the Moon will rise and set an hour later each day, becoming visible in the late afternoon and dusk sky as a waxing crescent which sets soon after the Sun. By first quarter, in a week's time, it will be visible until around midnight.
Its day-by-day progress is charted below, with all times are given below in Ashburn local time.
|Altitude of Moon
|Direction of Moon
|20 Sep 2017||19:07||19:39||2°||west|
|21 Sep 2017||19:05||20:10||8°||west|
|22 Sep 2017||19:03||20:42||15°||west|
|23 Sep 2017||19:02||21:15||20°||south-west|
|24 Sep 2017||19:00||21:50||24°||south-west|
|25 Sep 2017||18:59||22:26||28°||south-west|
|26 Sep 2017||18:57||23:07||30°||south|
At the moment of closest approach, it will pass within 2°52'of the Sun, in the constellation Virgo. The exact positions of the Sun and Moon will be:
|Object||Right Ascension||Declination||Constellation||Angular Size|
The coordinates above are given in J2000.0.
|The sky on 20 September 2017|
All times shown in EDT.
Never attempt to point a pair of binoculars or a telescope at an object close to the Sun. Doing so may result in immediate and permanent blindness.
The circumstances of this event were computed using the DE405 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).
This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.
|20 Sep 2017, 01:31 EDT||– New Moon|
|27 Sep 2017, 22:55 EDT||– Moon at First Quarter|
|05 Oct 2017, 14:41 EDT||– Full Moon|
|12 Oct 2017, 08:27 EDT||– Moon at Last Quarter|